Abstract: A pressure test cap includes a mounting collar with an outer rib to limit depth of insertion of the cap into a pipe. A closure disc which seals the mounting collar is connected to the collar through an inner rim by a weakened ring. An outer rim section registers with the inner rim so that impacts to the outer rim are transferred to the weakened ring to separate the disc from the collar. The closure disc includes a centrally positioned nipple for connection of a conduit of a pressurized test fluid source. The nipple is closed by a break-away nipple plug. The nipple plug has a centrally located indentation for piercing to bleed trapped air from the system and resealing by a screw.